Is that necessarily *r → j though? IIRC Chukchi /r/ is from PCK *ð, and *ð → j would sound somewhat more plausible (e.g. *d- → *j- is known from Proto-Turkic, and I've seen this also reconstructed as *ð rather than *d; palatal → dental has happened frequently in Australian langs).gach wrote:Also in Chukchi, though only to dissimilate two /r/s in consecutive syllables:
jara- < *ra-ra- ~ ra-
"house"
Also a similar shift *l → *ʎ → *j happened in Proto-Samoyedic (with exceptions in some positions, e.g. *lɤ → *lɤ, *Vla (? → *Vʎa) → *Vlä).
More on POA shifts, the assibilation "decay" of palatals is probably the most common example of an unconditional POA shift. E.g. PIE *ḱ across the various Satem languages yields
– Indo-Aryan *c → *tɕ → /ɕ/
– Nuristani *c → *tɕ → /tʃ/
– Lithuanian *c → *tʃ → /ʃ/
– Armenian and mainline Iranian *c → *tɕ → *ts → /s/
– Slavic and Latvian *c → *tʃ → *ʃ → /s/
– Albanian and Old Persian *c → *tɕ → *ts → /θ/
It'd be possible to put together a largely similar list for Vulgar Latin *c too.